Practice Questions

Q23.A capacitor of capacitance 150. 0 μF is connected to an alternating source of emf given by E = 36 sin(120πt) V. The maximum value of current in the circuit is approximately equal to: (1) 2 A (2) √2 A (3) 2√2 A (4) 1 A √2 → →

Q23.A wire of length 1 m moving with velocity 8 m s−1 at right angles to a magnetic field of 2 T. The magnitude of induced emf, between the ends of wire will be ___________. (1) 20 V (2) 8 V (3) 12 V (4) 16 V

Q23.A thin prism P1 with an angle 6° and made of glass of refractive index 1. 54 is combined with another prism P2 made from glass of refractive index 1. 72 to produce dispersion without average deviation. The angle of prism P2 is : (1) 6° (2) 1. 3° (3) 7. 8° (4) 4. 5°

Q24.A plane electromagnetic wave of frequency 20 MHz propagates in free space along x-direction. At a particular → → space and time E = 6. 6ˆj V m−1 . What is B at this point? (1) 2. 2 × 10−8ˆkT (2) −2. 2 × 10−8ˆiT (3) −2. 2 × 10−8ˆkT (4) 2. 2 × 10−8ˆi T

Q24.Two objects A and B are placed at 15 cm and 25 cm from the pole in front of a concave mirror having radius of curvature 40 cm . The distance between images formed by the mirror is: (1) 40 cm (2) 60 cm (3) 160 cm (4) 100 cm

Q24.A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should. (Select the best option) (1) Increase the wave length of the light (2) Increase the refractive index of the medium between the object and objective lens (3) Decrease the focal length of the eye piece (4) Decrease the diameter of the objective lens

Q24.A microscope is focused on an object at the bottom of a bucket. If liquid with refractive index 5 is poured 3 inside the bucket, then microscope have to be raised by 30 cm to focus the object again. The height of the liquid in the bucket is : (1) 75 cm (2) 50 cm (3) 18 cm (4) 12 cm

Q24.In a reflecting telescope, a secondary mirror is used to: (1) reduce the problem of mechanical support (2) make chromatic aberration zero (3) move the eyepiece outside the telescopic tube (4) remove spherical aberration

Q24.An ice cube has a bubble inside. When viewed from one side the apparent distance of the bubble is 12 cm . When viewed from the opposite side, the apparent distance of the bubble is observed as 4 cm . If the side of the ice cube is 24 cm , the refractive index of the ice cube is (1) 3 (2) 2 2 3 (3) 6 (4) 4 5 3

Q25.A point source of 100 W emits light with 5% efficiency. At a distance of 5 m from the source, the intensity produced by the electric field component is: (1) 1 W (2) 1 W 2π m2 40π m2 1 (3) 10π m2 W (4) 201 m2W

Q25.When one light ray is reflected from a plane mirror with 30° angle of reflection, the angle of deviation of the ray after reflection is: JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper (1) 120° (2) 110° (3) 140° (4) 130°

Q25.The threshold wavelength for photoelectric emission from a material is 5500 A . Photoelectrons will be emitted, when this material is illuminated with monochromatic radiation from a A. 75 W infra-red lamp B. 10 W infra-red lamp C. 75 W ultra-violet lamp D. 10 W ultra-violet lamp Choose the correct answer from the options given below : (1) B and C only (2) A and D only (3) C only (4) C and D only

Q25.Match List I and List II → → A Gauss’s Law in Electrostatics I ∮ E ⋅ dl = −dϕBdt → → B Faraday's Law II ∮ B ⋅d A = 0 → → C Gauss’s Law in Magnetism III ∮ B ⋅d l = μ0ic + μ0 ∈0 dϕEdt q D Ampere-Maxwell Law IV ∮→E ⋅d→s= ∈0 Choose the correct answer from the options given below : (1) A-IV, B-I, C-II, D-III (2) A-I, B-II, C-III, D-IV (3) A-III, B-IV, C-I, D-II (4) A-II, B-III, C-IV, D-I JEE Main 2023 (25 Jan Shift 2) JEE Main Previous Year Paper

Q25.A 2 meter long scale with least count of 0. 2 cm is used to measure the locations of objects on an optical bench. While measuring the focal length of a convex lens, the object pin and the convex lens are placed at 80 cm mark and 1 m mark, respectively. The image of the object pin on the other side of lens coincides with image pin that is kept at 180 cm mark. The % error in the estimation of focal length is: JEE Main 2023 (06 Apr Shift 2) JEE Main Previous Year Paper (1) 0. 85 (2) 1. 70 (3) 1. 02 (4) 0. 51

Q25.In Young's double slits experiment, the position of 5th bright fringe from the central maximum is 5 cm . The distance between slits and screen is 1 m and wavelength of used monochromatic light is 600 nm . The separation between the slits is: (1) 60 μm (2) 48 μm (3) 12 μm (4) 36 μm

Q25.The width of fringe is 2 mm on the screen in a double slit experiment for the light of wavelength of 400 nm. The width of the fringe for the light of wavelength 600 nm will be: (1) 4 mm (2) 2 mm (3) 1. 33 mm (4) 3 mm

Q25.The difference between threshold wavelengths for two metal surfaces A and B having work function ϕA = 9 eV and ϕB = 4. 5 eV in nm is: {Given, hc = 1242 eV nm } (1) 540 (2) 276 (3) 264 (4) 138

Q26.Electron beam used in an electron microscope, when accelerated by a voltage of 20 kV has a de-Broglie wavelength of λ0 . If the voltage is increased to 40 kV then the de-Broglie wavelength associated with the electron beam would be: (1) 3λ0 (2) 9λ0 (3) λ0 (4) λ0 2 √2

Q26.A proton and an α -particle are accelerated from rest by 2 V and 4 V potentials, respectively. The ratio of their de-Broglie wavelength is : (1) 8 : 1 (2) 2 : 1 (3) 4 : 1 (4) 16 : 1

Q26.Proton (P) and electron (e) will have same de-Broglie wavelength when the ratio of their momentum is (assume, mp = 1849 me ) (1) 1 : 1 (2) 1 : 1849 (3) 1 : 43 (4) 43 : 1

Q26.The light rays from an object have been reflected towards an observer from a standard flat mirror, the image observed by the observer are :- A. Real B. Erect C. Smaller in size than object D. Laterally inverted Choose the most appropriate answer from the options given below: (1) B and D only (2) B and C only (3) A and D only (4) A, C and D only

Q26.In photoelectric effect A. The photocurrent is proportional to the intensity of the incident radiation. B. Maximum kinetic energy with which photoelectrons are emitted depends on the intensity of incident light. C. Max K.E. with which photoelectrons are emitted depends on the frequency of incident light. D. The emission of photoelectrons require a minimum threshold intensity of incident radiation. E. Max K.E. of the photoelectrons is independent of the frequency of the incident light. Choose the correct answer from the options given below: (1) A and B only (2) A and E only (3) A and C only (4) B and C only

Q26.An electron accelerated through a potential difference V1 has a de-Broglie wavelength of λ. When the potential is changed to V2 , its de-Broglie wavelength increases by 50%. The value of ( V1V2 ) is equal to : JEE Main 2023 (30 Jan Shift 2) JEE Main Previous Year Paper (1) 3 (2) 49 (3) 3 (4) 4 2

Q26.If the two metals A and B are exposed to radiation of wavelength 350 nm. The work functions of metals A and B are 4. 8 eV and 2. 2 eV . Then choose the correct option (1) Metal B will not emit photo-electrons (2) Both metals A and B will emit photo-electrons (3) Both metals A and B will not emit (4) Metal A will not emit photo-electrons photoelectrons

Q26.If a radioactive element having half-life of 30 min is undergoing beta decay, the fraction of radioactive element remains undecayed after 90 min will be : (1) 1 (2) 1 8 16 (3) 1 (4) 1 4 2